Accessory hydraulic adjuster



April 15, 1952, E. A. RocKwELl.

ACCESSORY HYDRAULIC ADJUSTR Filed Oct. 6, 1945 5 Sheets-Sheet l Bw hm. NN,

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ACCESSORY HYDRAULIC ADJUSTER Filed oct. e, 1945 s sheets-sheet s llllll 165 n 155/ Jgg Jaa af rd' Patented Apr. 15, 1952 ACCESSORY HYDRAULIC ADJUSTER Edward A. Rockwell, shaker Heights, ohio, as-

signor, by mesne assignments, to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Application October 6, 1945, `Serial No. l620,753

l My invention relates particularly to a device for accurately and effectively controlling the clearance .in pulsator devices and which .is applicable to many diierent types of devices, but which has especial applicability, for example, in the lcontrol of clutches, brakes, or other `accessories in automobiles, airplanes, etc. n The object of my invention is to provide a pulsator mechanism which Will effectively control the -cl-earance, etc., in apparatus .of the above character. Another object is to provide a device of this kind which is readily applicable to variations in clearances of the devices to be controlled thereby. Another object is to provide a mechanisrn of this kind in which theclearance distance and clearance volume may be sharply Yand accurately measured. A further object is to provide such a mechanism, which is capable of adjustment to alter the clearance distance -and volume thus measured. A further vobject is to provide a pulsator motor .having a differential piston arranged to be operated by a low pressure to deliver a higher pressure followed .by the unseating of a valve to deliver a lower pressure, thus rapidly .taking up the clearance in the work-performing device, so as to determine sharply the take-up stage of the operation, inasmuch as the diierential pressure will hold the piston advanced, without seating the valve, until the differential pressure has been overcom-e in the release of the pedal, thus accurately measuring oit the clearance volume on the return stroke of the piston. This is accomplished by the differential piston pressure being exerted against a piston return spring. In

this way, on the retraction of the piston the predetermined clearance distance and volume become accurately and sharply reconstituted. Thus, one of the important objects of my invention is to provide in the pulsator a differential piston arranged to deliver initially a higher pressure than the pressure received on the piston so as to intensify the sharpness'pf the point at which the chang-e is made from one pressure to another in the delivery of the hydraulic fluid for operating kthe Work-performing device, such, for instance, as

a clutch or brake. Still another object is to provide a plunger with a cylinder for the same having a clearance volume which may be adjusted. Further objects of my invention will appear from the detailed d-escription of the same hereinafter.

This arrangement overcomes the great disadvantages rencountered in the prior devices intended as clearance or slack adjusters, as in the latter there was no accurate adjustment of the clearance volume of liquid supplied for taking up the clearance. This was due to the fact that, without the differential piston, for example, in the prior devices on the relaxation of any particular pedal braking pressure -being applied the valve immediately seated at the variable pressure be- 16 Claims. (Cl. (iO-54.5)

ing applied thus producing a variable clearance volume, which, also, changed not only with the wear of the partslcontaining the clearance but with the chang-es of temperatures of the parts due to the heat producing expansion, as for `lnstance in brake drums, on account of atmospheric temperatures, friction etc. In said prior devices, the increase of clearance volume of vliquid transmitted thereto, due to the heating eiiects, etc., prevented the accurate return to the Voriginal clearance volume, and, in the case of brakes, upon cooling they would drag. My clearance adjuster adequately and accurately adjusts in either direction to th-e clearance volume desired :andthe clearance distance.

While my invention "is capable of embodiment in many different forms, for the purpose of illustration I have shown only certain forms of .the same in the accompanying drawings, iin which:

Fig. 1 is a longitudinal vertical section of 'a clearance adjuster made in accordance with .my invention, shown as attached to an automobile clutch for the operation `of the same, the clutch being shown in its normally engaged position;

Fig. 2 is a similar vertical sec-tion of a portion of the same, showing the differential measuring piston at the point of zero clearance between the clutch fingers and the clutch throwout bearing with the clearance adjuster valve .just beginning to open;

Fig. .3 is a similar view of the same showing the differential measuring piston at the end of its path of travel and with the clearance adjuster valve fully open; l

Fig. 4 is a vertical longitudinal section of a modified form of clearance adjuster showing the same as incorporated in the same casing with the master cylinder; l

Fig. y5 is a vertical longitudinal section of another modication of my invention;

Fig, 6 is a longitudinal .section of a further modification of my invention; l

Fig. 7 .is an end elevation of the same;

Fig. 8 is a diagrammatic vertical section of a slack adjuster .made in accordance `with my invention, as applied to a normally closed clutch;

and

Fig. 9 is a diagrammatic vertical section `of my invention as applied to a normally open :clutch or a brake system. j

In the drawings, .reference first to Figs. v1 to 3, I have shown a pedal I having a fixed pivot .2 carried on a chassis of an automobile (not shown) The lever I is connected by a link 3 to a yoke coupling 4 on a piston rod 5 having 4around the same a leather boot 6 fastened by a ring Fl in a groove 8 on the yoke coupling 4. The said -boot 5 is fastened by another ring 9 in a groove llly on a master cylinder casing Il. Said casing Il i535 hasapertured ears 12forattachment cfthemaster cylinder to the automobile chassis. The said master cylindenfurthermore, has a liquid reservoir I5 provided with a filling opening I6 having a closed cap I1 and vent openings I8 as well as a sealing gasket I9. In the lower portion of the cap I1 there is a disc 20 having off-set ears 2I around the margin to provide apertures22 in communication with the vent I8. The plate 26 supports an annular balile 23.

The said reservoir I5, furthermore, has liquid compensation openings 24 and 25 communicating with a cylindrical chamber 26 in which there is arranged to reciprocate an impulser plunger or piston 21 provided with a recess 28 to receive the piston rod 5. At its forward end the cylinder 26 is provided with a ring 29, to limit the movement of the piston 21, which is held in place by a split ring 30. A sealing ring 3I seals the iront end of the piston 21 and the latter is provided with an annular recess 32 communicating with longitudinal passageways 33 passing through the piston 21 so as to communicate with a flanged rubber ring 34 acting as a valve, secured to the rear face-of the piston 21. A helical spring 35 resting against the rubber ring 34, is supported by a ring 36 from a shoulder 31 in the cylinder 26. Also, a discharge port 38 is located at the rear end of the cylinder 26, the same having screwthreaded therein a reduced portion 39 of a screw threaded adjustable casing head 4, having a hexagonal portion 4I for adjustment thereof, in a valve assembly or clearance adjuster cylinder casing42 which is adjustable on the screw-thread carried by the adjustable casing head 48. An annular seal 43 seals the head 40 in the cylinder 42 and a longitudinal inlet port or passageway 44 is provided in the head 40 so as to connect the master cylinder chamber 26 with the interior of the cylinder 42. It will be noted that the cylinder 42 has within the same a large cylindrical chamber 45, provided with a breather port 45a and a cylindrical chamber 46 of a smaller diameter, so as to receive therein a differential plunger 41 having annular seals 48 and 49 on a large piston 50 and on a small piston 5I, respectively. At the rearward end of the dierential plunger 41 there is an annular extension 52 acting as a guide for a helical return spring 53, one end of which is seated against a disc 54, having openings 55 therein, and the other end of which is received on the rearward end of the differential piston 41. During the work stroke the force of this spring 53 is less than the differential force acting on the pistons 58 and 5I. The openings 55 communicate with a screw-threaded discharge or delivery opening 56 in the clearance adjuster cylinder 42. The said disc 54 is arranged to act as a stop for a rearward end 51 of a valve rod 58. Near the end thereof there is a spring retaining ring 59 fastened thereto for holding in place a spiral spring 60 supported on the rearward end of the diierential plunger 41 within the annular spring guide 52. The middle portion of the valve rod 58 is provided with a plurality 0f flutes 6I around the same within a longitudinal passageway 62 in the differential plunger 41. Near its forward end the 'valve rod 58 has a reduced neck portion 63 adjacent to a conical Valve 64, acting as a trapping means, integral with the valve rod 58 and which is arranged to seat on a valve seat 65 located on the forward end of the differential piston 41. On top of the conical valve 64 there is secured an annular rubber valve 66 supported by a flat ring 61 having a screw 68, so that said rubber valve ring 66 can seat -against a valve seat 4 69 on the rear face of the cylinder head 46 to provide an eiective seal between the inlet passageway 44 and the longitudinal passageway 62 which traps the accurately determined amount of liquid in the chamber 46 between succeeding strokes of the pistons 58, 5I, which cylinder head 40 is adjustably screw-threaded within the clearance adjuster cylinder 42.

Fig. 1 shows the clearance adjuster as being connected, by a pipe having a screw-threaded fitting 1I, to a screw-threaded fitting 12 in a ring 13 located within a clutch housing 14 of an automobile, and which contains a conventional clutch assembly normally in engagement. As shown in Fig. l the clutch 15 comprises a y wheel 16 driven by a motor shaft 11 arranged so as to transmit power to a driven shaft 18 by means of a friction clutch disc 19 slidably connected by splines 89 to the driven shaft 18. The friction disc 19 is arranged to be brought into engagement with the fly wheel 16 by means of a pressure plate 3l mounted on the fly wheel 16. said plate having rthereon a plurality of pivoted radial clutch fingers or elements 82. The clutch fingers or elements 82 are operated by means of a throw-out ball bearing ring 83 mounted on a sleeve or motor plunger 84 which is supported on the bushing 85 on the shaft 18 and which has a cylinder or enclosure 84a and a retracting spring 84h engaging a flanged ring 84e for withdrawing the bearing 83 and sleeve 84 or motor plunger through the range of slack, said elements 82 being arranged to move and to be moved by the motor plunger 84. The pipe 19 communicates with an annular chamber 86 around the bushing 85 so that the force of the hydraulic liquid from the pipe 10 can bear upon the rear end of the sleeve 84 around which there is a sleeve 81 having an annular seal 88 sealing it on the outside of the sleeve 34. The movement of the sleeve 84 to the left, in Fig. l, will move the throw-out bearing 83 rst to take up the clearance between the same and the ends of the pivoted fingers 82, at which point the valve 64 will begin to open, and further movement of the sleeve 64 tothe left will disengage the clutch 15, by swinging the fingers 82 on their pivots 89, which are carried on a casing member 96 connected to the y wheel 16, inasmuch as the fingers 82 have pivotal connections 9I with the pressure plate 8l. A return means, in the form of a plurality of return coil springs 92 carried on bosses 93 secured to the plate 8| and on bosses 94 formed on the casing member 98, normally moves the plate 8| to the left to bring about the engagement of the clutch disc 19 between the fly wheel 16 and the pressure plate 8i at successive stop positions due to wear of the friction faces of the y wheel 16 and the plate 8l as well as of the discs 19.

The hydraulically operated mechanism comprising the sleeve 84, for moving the throw-out bearing 83 toward and into engagement with the ngers 82, is shown and described in detail in my copending application Ser. No. 515,602, upon Hydraulic Motor Operated Clutch, filed December 24, 1943 now Patent No. 2,501,005.

In Fig. 2 I have shown a portion of the valve as it will appear with all the clearance taken up between the fingers 82 and the throw-out bearing 83, that is to say, at a time when the valve 64 has begun to open by reason of the valve rod end 51 contacting with the apertured stop disc 54.

As shown in Fig. 3 the further movement of the pedal I will continue until the valve 64 is entirely open andthe clutch disengaged by the pressureplate 8|' being freed from the friction disc 'I9 and the fly wheel 16.

In Fig. `4 I have shown a modicaticn of the clearance'adjuster which, it is understood, is to be connected into the system the same as already describedl and shown in Fig. 1.

`clearance adjuster cylinder 91, and in addition an annular chamber |02 connected by a passageway |03 to the reservoir l5. A reduced forward end |04 of the clearance adjuster cylinder is provided with a seal |05 within the cylinder casing 98. It will be noted, furthermore, that the annular chamber |02 is connected by a breather port |09 to the interior of the clearance adjuster cylinder 9-1 where it communicates with a large cylindrical chamber 01 which is adjacent to a smaller cylindrical chamber |09 therein. Reciprocable within the chambers |91 and |08,

there is provided a plunger having a large piston |09 and a smaller piston ||9, the former having an' annular seal and the latter having an annular seal ||2. The piston |I0 has at its rear end a guide ange I .|3 for a helical spring Illi seated around the same, the other end of the spring ||4 resting against a stop disc |I5 which is--provided with apertures ||6 communicating with the discharge port |00. Also, in'` the pistons I 09 and ||lthere is a longitudinal passageway I |1 having therein a valve rod I l'providedvwith an end I |'9 to 'cooperate with the stop disc H5. The valve rod I I 8 also has a spring retaining ring secured thereto for maintainingv in place a spiral spring 2| seated on the rear end of the piston ||0. 4This valve rod ||8 has a fluted portion |22,. also a reduced forward portion |23 provided with a conical valve |24 thereon which is arranged to seat on a valve seat |25 on the forwardl end of the piston |99. The said conical valvel |24, furthermore, carries on its forward facev a disc |20 provided with an annular rubber valve |21' which cooperates with a valve seat |28 ori-'the master cylinder casing 98, and which is' held in place by a screw |29. l

In the modified form of my invention shown in Fig. 5 I have provided an end plate |39 having a screw-threaded inlet port |3| for attachment of a hydraulic connection to a master cylinder such as is shown in Fig. l. The plate is. attached by bolts |32. to a dilerential plunger housing |33 having a large cylindrical chamber |34 and a small cylindrical chamber |95 pro,- vided with a breather space.l |36 between the same, connected to the outer airl by a vent I3?. A valve seat ring |38 is located in the plate |30 to receive an annular valve |39 fastened to a valve stem I 40 by a screw end |4I and a nut |42. The valve stem |49 has thereon a conical valve |43 having a valve-seatingv spring |95. thereom held 4in place by e Split ring |45 carried in a recess in the interior of a cylindrical chamber |46 in a tubular extension |41 on a large piston |48'. The piston |48 has a shoulder In this instance1 I have provided the same parts as shown in Fig. l

|49 Vcarrying annular lipseal |50 having thereon a spiral spring |5I supported by a split ring |52 in a recess on the` outside of the tubular extension |41. The conical valve |43 seats on a Valve seat ring |54 in the large piston |48 and on its small end the conical valve |43 has a fluted valve rod |55 having an end |58 which contacts in its` end position with an adjustable screw-threaded rod or casing head |51 having a seal |58 and a lock nut |59. A screw-threaded outlet opening |60 conveys the hydraulic fluid to a clutch or brake which is operated thereby after taking up the clearance therein. Attached to the large piston |98 there isa smaller piston ISI having a lip seal |82 and a helical spring |03, the latter being seated against a retaining guide sleeve |54 around the iluted valve rod |55 and seated on the lip seal |62, located in a chamber |65 connecting with the outlet port |80. This arrangement is such that whatever the position of adjustment of the sleeve |54, at the time of closing the valve |43 on the return movement of the pistons |48 and IGI the spring |63 will always have the same force exerted due to its compression as the force of the differential 'pressure from the pistons |48 and I6I.

The modication of my invention shown in Figs. Grand '7 is constructed similarly to the form of my invention illustrated in Fig. 5. In the said Fig. 6, just as in Fig. 5, I have shown the inlet |8| onthe cylinder head |30 fastened by the screws |32 to a ange on the cylinder |33, said cylinder head having, as in Fig. 5, the yielding valve seat |38. However, seating on the valve seat |38 there is a disc-shaped valve |95y having an annular valve element |51, toA coopcrate with said valve seat |38, formed by an annular recess |58 in disc- |65 and secured to a conical valve |09 on a valve stem |10 which passes through a longitudinal cylindrical passageway |1| in a differential plunger |12, which has a large piston |13 provided with a peripheral seal |14 reciprocating in a large cylindrical chamber |15 in the cylinder |33. At one end of the passageway |1| there is a rubber valve seat |18 to cooperate with the conical valve |69. A breather opening |11 is connected tothe large cylindrical chamber |15. The said plunger |12, furthermore, has at one end a small piston |18 which is provided with an annular seal |19 and which reciprocates in a small cylindrical chamber` |80. Within the passageway `|1|, furthermore, there is an enlarged cylindricalV recess |8| to receive a helical spring |82 held in place by a split ring |83 located around the valve stem |10, in order to urge the conical valve |69 into seated position. Outside of the spring |82 there is a larger helical spring |84 which seats against the small end of the plunger |12, the other end of which is carried within a cylindrical shell 85 fitting within the casing |33, said shell |85 having a number of holes |86 to permit the passage of hydraulic nuid to the dis.- charge or delivery port |60. The cylindrical shell |05 is supported upon one end of an adjusting screw |81, which screw has a locking nut |88 disposed on its other end. An annular seal |89 provides a tight joint on the outside of the adjusting screw |81. The said adjusting screw thus supports the end of the cylindrical shell |85 which in this way forms an abutment for cooperating with the end |58 of the valve stem |10. Ears |90 having holes |9| provide means for attaching the slack adjuster wherever desired. l

In Fig. 8 I have shown a diagrammatic illustration of the form of the apparatus as applied to a normally closed clutch system. In this instance I have provided the master cylinder having the reservoir and piston 21, as illustrated in Fig. 1, which has a hydraulic connection |92 to a slack adjuster |93 which may be constructed in the same manner as the slack adjuster in the casing |33, as shown in Fig. 6. This is provided with the differential pistons |13 and |18. A delivery pipe |94 leads to one end of a motor cylinder |95 which has a motor piston |96 therein and is provided with a sleeve |91 having a flange |98 for retaining a retracting spring |99 in place for retracting the motor piston 4|96 through the clearance range, inasmuch as the spring |99 is supported at its other end on a xed support 296. The motor piston |96 has, as shown diagrammatically therein, a small extension 29| to provide, in the starting position of the apparatus, a clearance 262, which isadjustable according to the position of the screw |81, with regard to the stop position of an end 203 of an arm or element 204 on a bell crank lever 265 supported on a pivot 256 from a xed bracket 201, which is shown diagrammatically as having an adjustable screw 298 in a bracket 299 on the iixed bracket 201. Another arm 2|0 of the bell crank lever 265 has a pin 2|| connected to a spring-supporting plate 2|2 supported on one end of a return spring 2|3 having at its other end a spring-supporting plate 2| 4 carried on an abutment 2|5 on a xed support 2|6. This figure is a diagrammatic representation of a slack adjuster arranged for operating a normally closed clutch system, the screw 268 being representative of the varying positions of the clutch in the progressive wear of the friction surfaces therein in successive operations of the clutch.

The diagrammatic illustration in Fig. 9 represents the system as applied to a normally open clutch or brake system. In this instance the master cylinder and slack adjuster |93 are constructed just the same as in Fig. 8. Also, a motor cylinder 2i1 and a motor piston 2|8 with an extension 2|9 are provided the same as in Fig. 8. In this instance, however, the extension 2|9 bears against a bell crank lever 220 on a fixed pivot 22| and the bell crank lever 220 has an arm or element 222 which bears at all times against the extension 2| 9 against which it is urged by a return or retracting spring 223 arranged in the same manner as the spring 2|3 in Fig. 8 except that in this instance the spring 223 is mounted nearer to the pivot 22| on an arm 224 and the outei` end of said arm has a screw-threaded abutment 225 provided With a head 226. This screw 225 represents partly the successive stop positions, as in the case of the screw 208, due to the progressive wear on the friction parts of the clutch. In other words, the position of the said screw 225 may represent wear on the brake shaft according to the adjustable positions on the screw head 226 which establishes in the operation of the slack adjuster a clearance 221 with regard to a plate 228 supported by a spring 229 which is retained in a spring housing 239. The lower end of the housing 236 rests upon the upper end of the screw 23| screw-threaded in a fixed support 232 which, by its position, represents the wear on the brake drum in successive positions.

In the operation of my invention, referring first to Figs. 1 to 3, the clutch 15 will be normally in engagement, as shown in Fig. 1, with the piston 21 withdrawn to the left in said iigure, the valves 64 and 66 being seated, and Withj the clutch throw-out bearing 83 being out vof contact with the clutch fingers 82. When the pedal is operated the liquid received through the port 25 from the reservoir I5 into the master ycylinder 26 will be discharged therefrom to the outlet opening 38, thus closing the equalization passageway 25. The pressure of the liquid in the passageway 44 will unseat the valve 66 and move the pistons 50 and 5| to the right while maintaining the valve 64 closed and thus delivering from the smaller cylinder 46 to the clutch, initially, to the sleeve 84, the liquid trapped in the smaller cylinder 46 under higher pressure than the liquid which is received from the master cylinder into the cylinder 45 due to the difierential sizes of the pistons 50 and 5| therein. This will continue until the clearance volume of liquid present in the smaller cylinder 46, at the right of the piston 5 I, in Fig. 1, will have brought the throw-out bearing 83 into contact with the fingers 82, as shown by dotted line at A, Whereupon the valve' 64, 65 will unseat by reason of the end 51 of the valve rod 58 contacting with the stop plate 54. When the point where the valve 64, 65 becomes unseated is reached the low pressure liquid from the passageway 44 will pass out through the pipe 13 so as to move the sleeve 34 farther, as shown by dot-dash lines at B, and thus disengage the friction disc 19 from the adjacent surfaces of the iiy Wheel 16 and the pressure plate 8|, thus releasing the clutch. When it is desired to engage the clutch again the manual pressure on the pedal is relaxed until the parts are again. in the position of the initial contact, as shown at A, the piston 5|.

prior and up to such time having remained in its advanced position due to the diierential pistons 59, 5| providing a force overcoming the force of the return spring 53. At this time, which is also theQtime when the valve stem 51 leaves the stop 54, the valve 64, 65 closes quickly and sharply, always at the point when the same identical differential of pressures on the pistons 5|) and 5| permits its closing, under the influence of the spring 68 and the relative sizes of the cylindrical chambers 45 and 46, thus establishing at the time of closing of the valve 64, 65, an laccurate and definite volume of clearance liquid in the small cylinder 4'6 at the right of the piston 5|, in Fig. 1, for the next pulsator stroke and which volume is accurately maintained until the next stroke of the pistons 50 and 5I to the right, in Fig. 1. Accordingly, this volume will always remain the same in succeeding strokes for the operation of the clutch or brake or other device being operated thereby, unless altered by adjustment. However, it will be understood that this volume can be adjusted at Will by changing the position of the casing head 40 within the clearance adjuster cylinder 42. tion of the master cylinder piston 21 it Will be noted that if for any reason the volume of liq-A uid in the master cylinder piston chamber has decreased, compensating liquid can enter the same through the passageways 24 and 33 past the rubber cup 34. Normal compensation takes place in the retracted position of the piston 21 through the port 25.

The modified form of my invention in Fig. 4 operates in substantially the same manner, but in this instance the adjustment of the clearance volume is obtained by the adjustment of the In the retracsleeve cylinder casing 91 within the mastercylinder casing 9.8i, the adjustment being maindigiferenti-al. piston |48, I6| by the adjustable screw-threaded` rod or casing head T-contactingA the valve rod end |56., thus effectively ad.- iusting the available clearance volume.

It will be understood, of course, that the clearance adjuster in. any of the forms above dei scribed can be applied, instead, to the operation of afnormally open. clutch or a brake, as for instance on.4 an; automobile or airplane, or in fact in the operation of any other apparatus for per` forming work, in which itis desired to rst take up the clearance and then to` operate the apparatus,y further, thereby.

f Referring to4 the operation of: the slack ad- `luster illustrated in Figs. 6 and '7, inasmuch asV this. form of my invention. is arranged for the operation of a. normally closed clutch, the operation is. substantially the same as in the form of my V`invention shown in Fig.. 5,:v except that in.. this instancev the valve seating spring |82 is located at. the same end of the plunger |12 as the spring (81;. whereas the valve seating spring IM is at the other end of the. plunger in Fig. 5.. This ar- 1 rangement. of the.v spring |82 in Fig. 6, therefore,

renders itl more accessible.v

In', the operation of the diagrammatic representation of the normally closedv clutch system equipped withv my invention, 'as shown in Fig. 8',

the operation. thereof will continue to maintain inthe starting position of. the successive operas an accurate and dependable slack: adjustmentY l paratus being operated by the impulser.

Thev diagrammatic representation of a brake system or normally open clutch system illus-- trated in Fig. 9, operates 'in substantially the. same manner as the clutch adjuster in Fig. 8` ex-A cept in this instance the motor piston is. returned` by the spring 223` and the clearance" is. thus". not located between the motor piston lil and the' armi or elementi Z22-of the bell crank lever 2:20, butis1locatedat22'l, between the-screw head 22S and the: spring retainer plate 228', and. accordingly, the screw head wouldbe. comparable` to abrake shoe in the braking. system and` the spring retainer plate 228 would be comparable to the brake drum in such system. Also, in the. case. of av normally open clutch system, the screw; head 226` and the spring retainerplate. 228` would be. comparable. to the two friction surfaces onY the fly wheel and' the pressure plate of! the normally open clutch. v

While I have described my invention. above in detail, I` wish it to be understood that many changes may bemade therein without departing from the spirit of the samel.

I claim:

l. The combination of a pulsator mechanism, a casingl havingY a hydraulic inlet and a hydraulic outlet, a large piston member near the inlet, a smaller piston member near the outlet.'

means for retraeting the piston: members, a valve` associated with said piston members, means forv unseating the valve by movement of the piston members toward said outlet; and. disengageable mechanism,A comprising a lever and asleeve,l dis'- engaged from. the lever by the movement.' of: the liquidV from. the hydraulic inletA after the une` seating of. the. valver said mechanism being provided with a, clearance between. the lever and said sleeve taken up by the Iquidsupplied from. the piston members before unseatingl the valve.

2; The combination of a pulsator mechanism," a casing having a hydraulic inlet anda hydraulic outlet a large piston member near the inletQa smaller piston member near the outlet, means for retracting the piston members-,.- a valve associated with said pistonmembers, means for unseating the valve by movement of thepi'ston members tow-ard. said outlets and'.` a work perform:-V ingv device, comprising a lever and. anannular bearing, disengaged fromI the lever by the movement of the liquid from the hydraulic inlet. after. the unseating ct theY val-ve.. said devicelfusing provided with aiv clearance between'. the leverand. said annular bearing takenup bythe liquid sup--` plied from the pistonrnembers before lunseating thevalve. A 3. In; a pulsator mechanism,. a casing havinga. hydraulic inlet.4 and a hydraulicoutletr a." large piston mem-ben near the inlet,l a smaller piston member near the outlet, said. members beingconf nected together,A meanst for retracting the piston members, a. valve associated with .said` pistons. and means for unseating, `the valve by movement of the pistonniembers toward said outlet, said pis-n tenl members having carried thereby, also,l aval-ve having said-leasing as its valve seat for cuttingo the access of liquid` from the inlet when the piston members are in retracted posi-tien.`v

The. combination of a. pulsatcr mechanism, a casing having a` hydraulic inlet andA ahy-f drau'lic outlet, 4a large.- piston member near the inlet/,7. a smaller piston member near thekt outlet,- rnean-sfor retracting the piston-members? a valiseK associated with said pistonY members, Incans-ttulunseatingJ the valve movement. ofthepistcn: members tcwvardv said1 outlet-, A and dlsengageable mechanism` disengagedby the movement di Y the liquid fremthe hydraulic inlet after the unseaftf ing er the valves and being `pu-ovidedvri-thea@ clearance taken. up by the' lieu-idT suppliedfrom'. the piston members before the unseatini the valves said pieten-members havnacarred muerebr; also.;1 a valveflbated on the larsepi-ston 'hav-5 ing said casi-ng; as its valve reati for cutting off-the accessfof: liquid from the inlet when thelarge; piston member is' inrretractedF posi-tion.` f

Tn-In a. pulsator operating arrangement cludingfmeansdenine a pulsatormotorimeansl applying` a retracting, force: te: said pulsator-mc: tor, a delivery and return; valve assembly forfcen'f` trolling the: operating pressurevto. and from:` said:- pulsator motor,A said valve; comprising meansf'efd fectiye'to deliver a high range of' pressures. there-4 througlr. means including.: a; diderential: piston:

" carrying a; valve and a. travel'.controlleri;r opening device for said valve arranged to open the v-alve atfthe differential pressure present during the differential piston travel, sharply responsive to the delivery thereto of a selected value of pressure below said range effective to shut olf uid communication therethrough, and means responsive to the continued delivery of pressure fluid from: s-aid pulsator motor by virtue of the action of said retracting means effective to displace a selected measured quantity of additional fluid from said pulsator determining precisely the movement of said pulsator in the retracted position following the closure of said shut off means.

6. In a pulsator operating arrangement including means defining a pulsator motor, means applying a retracting force to said pulsator motor, a delivery and return valve assembly for controlling the operating pressure to and from said pulsator motor, said valve comprising means effective to deliver a high range of pressures therethrough, means including a differential piston carrying a valve and a travel controlled opening device for said valve arranged to open the valve at the differential pressure present during the differential piston travel, sharply responsive to the delivery thereto of a selected value of pressure below said range effective to shut oif fluid communication therethrough, said means comprising a check valve having a travel controlled opening device for said valve, and means responsive to the continued delivery of pressure fluid from said pulsator motor by virtue of the action of said retracting means effective to displace a selected measured quantity of additional fluid from said pulsator determining precisely the movement of said pulsator in the retracted position following the closure of said shut off means.

7. In a pulsator operating arrangement including means defining a pulsator motor, means applying a retracting force to said pulsator motor, a delivery and return valve assembly for controlling the operating pressure to and from said pulsator motor, said valve comprising means effective to deliver a high range of pressures therethrough, means including a differential piston carrying a valve and a travel controlled opening device for said valve arranged to open the valve at the differential pressure present during the differential piston travel, sharply responsive to the delivery thereto of a selected value of pressure below said range effective to shut off fluid communication therethrough, said means comprising a check valve as well as a supply cut-off valve, and means responsive to the continued delivery of pressure fluid from said pulsator motor by virtue of the action of said retracting means effective to displace a selected measured quantity of addtiional fluid from said pulsator determining precisely the movement of said pulsator in the retracted position following the closure of said shut off means.

8. A device of the character described including, housing means including fluid connections thereto, means defining a rst pressure-responsive area and a second pressure-responsive area. positive means connecting said areas together, said rst area being in communication with a first one of said fluid connections, and said second area being in communication with the other one of said fluid connections, the difference in areas between said two pressure-responsive areas permitting a differential force to produce movement in one direction, when said areas are subjected to the same unit pressure, means appiymg a predetermined value counteracting force to said differential forcefa cut-off valve interposed between said uid connections, stop means responsive to a predetermined travel position of said positive connecting means in one direction effective to cause the opening of said valve arranged to open the valve at the differential pressure present during the differential piston travel to provide free flow between said fluid connections and responsive to movement of said positive connecting means in the opposite direction effective to cause closing of said valve.

9. In a device of the character described, including means defining a pulsator pressure fluid flow control valve arrangement, said means comprising, a housing having a stepped bore including a first cylindrical portion joining with a second cylindrical portion having a reduced cross section, a rst port in said first portion, a second port in said second portion, means defining a valve assembly proper including a tubular-like member provided with a first pistonlike portion received in sealed reciprocable relation within said first bore and joined with a.

second piston-like portion received in sealed slidable relation within said reduced portion, the difference in piston areas providing a differential control area, a valve seat facing in the direction of said first named port and being located in the terminal of said tubular member adjacent to said flrst piston portion, a valve cooperating with said seat means responsive to movement of said valve assembly by the delivery of pressure through said first named port to effect the opening of said valve arranged to open the valve at the differential pressure present during the differential piston travel to provide flow through said housing and said second-named port, resilient means normally urging said valve in the direction of engagement with said seat, means normally urging said valve assembly in the direction of said first-named port with a selected predetermined force.

10. In a pulsator mechanism, a casing having a hydraulic inlet and a hydraulic outlet, a retractable differential plunger movable by the incoming liquid towards the outlet, a valved 'passageway to opposite sides or the plunger to connect the inlet to the outlet when open, and stop means for opening the valve at the differential pressures present during the differential piston travel when the plunger has been moved towards the outlet, said mechanism being constructed to retain the valve open after a relaxation of the pressure in the inlet Luntil a predetermined pressure has been reached in the outlet.

11. In a pulsator mechanism having an impulser, a casing having a hydraulic inlet and a hydraulic outlet, a retractable differential plunger movable by the incoming liquid towards the outlet, a valved passageway to opposite sides of the plunger to connect the inlet to the outlet when open, a motor plunger and cylinder connected to said outlet to be moved the same distance by the liquid received therefrom on successive operations of the impulser notwithstanding successively different starting positions of the motor plunger, and means for opening the valve at the differential pressures present during the differential piston travel when the plunger has been moved towards the outlet, said mechanism being constructed to retain the valve open after a relaxation of the pressure in the inlet until a predetermined pressure has been reached in the outlet.

13 12. In combination, a pulsator having a displaceable impulser plunger and a cylinder therefor, a jiiydraulic clearance adjuster, having an inlet port and a delivery port, hydraulically connectedto the impulser, a motor plunger and cylinder having a hydraulic connection to said delivery port, a retracting device connected to the motor plunger, an engaging element arranged.' to move the motor plunger and to be movable by the motor plunger, a second element engaging therewith, and means arranged to return said rst mentioned element to successively variable stop positions during successive operations of the impulser, said clearance adjuster comprising retractable differential measuring means to trap the liquid between the clearance adjuster and the motor plunger when the impulser plunger is in its undisplaced position and to release the said trapped liquid to the lhydraulic connection between the motor plunger` and the clearance adjuster when the impulser plunger hasv been displaced to `a predetermined extent but to ltrap liquid again when the first mentioned element reaches its stop position so.. as to establish thereby the same predetermined amount of clearance between the motor plunger and said second mentioned element ateach successive operation of the impulser, notwithstanding wear of the second mentioned element.

13. -In combination, a pulsator having a displaceable impulser plunger and a cylinder therefor, ah'ydraulic clearance adjuster, having an inlet port and a delivery port, hydraulically connected "to the impulser, a motor plunger and cylinder .having a hydraulic connection to said deliverypert, a retractng device connected to the motor plunger, an engaging element arranged to movethe motor plunger and to be movable by the motor plunger, a second element engaging therewith, and means arranged to return said first mentioned element to successively variable stop positionsv during successive operations of the impulseffsaid clearance adjuster comprising retractable differential adjustable measuring means to trap-the liquid between the clearance adjuster and the .motor plunger when the impulser plunger is in its'undisplaced position and to release the said trapped liquid to the hydraulic connection between the motor plunger and the clearance adjuster when the impulser plungerlhas been displacedto a predetermined extent but to trap a predetermined adjustably variable volume of liquid again when the first mentioned element reaches j its stop position so as to establish thereby.` the same predetermined adjustable amount ofclearance between the motor plunger and said second `mentioned element at each successive operationoi the impulser, notwithstanding wear of the second mentioned element.

l4.ln,combination, a pulsator having a displa-ceabler impulser plunger and a cylinder therefor, a hydraulic clearance adjuster, having an inlet porti and a delivery port, hydraulically connected to the impulser, motor plunger and lcylinder-iihaving a hydraulic connection to said delivery port, a retracting device connected to the motor plunger, an engaging element arranged to move/the motor plunger and to be movable by the motor plunger, a second element engaging therewith, and means arranged to return said first-mentioned element'v to ,successively variable stop positions during successive operations of the impulser, said clearance adjuster comprising retractable differential measuring means having a valved plunger and cylinder to trap the liquid between the clearance adjuster' and the motor plunger When the impulser plunger is in its undisplaced position and n to release the trapped liquid to the hydraulicconnection between the motor plunger and the clearance adjuster when the impulser plunger has been displaced to a predetermined extent but to trap liquid again when. the first-mentioned element reaches its stop position so as to establish thereby the same predetermined amount of clearance between the motor plunger and the secondV mentioned element at each successive operation of the impulser, notwithstanding wear of the second mentioned element.

15. In a pulsator mechanism, a casing having a hydraulic inlet and a hydraulic outlet, a large piston member near the inlet, a smaller piston member near the outlet, means for retracting the piston members, a valve associated with said piston members, and Vstop means for unseating the valve by movement of the piston members toward said outlet, said piston members being connected together and having a valve seat for said valve arranged to be moved away from said valve at the differential pressures present during the differential piston travel by the diierential pressure on said piston members when the valve is unseated by said means.

16. In a pulsator mechanism, a casing having `a hydraulic inlet and a hydraulic outlet, a large valve at the diierentia1 pressures present duringV the differential piston travel by the differential pressure on said piston members when the valve is unseated by said means and to be returned to the valve when the pressure` has been relaxed sumciently for the movablevalve seat to reach the stationary valve.

EDWARDA A. ROCKVJELL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 697,140 Goldschmidt Apr. 8, 1902 2,156,120 LaBrie Apr. 25, 1939 2,229,055 Dick Jan. 24, 1941 2,345,811 Harp Apr. 4, 1944 2,385,625 Hopmans Sept. 25, 1945 FOREIGN PATENTS Number Country Date 358,126 Great Britain Oct. 8, 1931 365,069 Great Britain Jan. 6, 1932 389,930 Great Britain Mar. 30, 1935 504,278 Great Britain A-pr. 19, 1939 547,465

Great Britain Aug. 28, 1942 

